Class is back in American discourse. It has become impossible to deny—and strange that it was ever possible to deny—that your inheritance, income, and credentials guarantee certain advantages, and that these advantages might have been wrested from those less fortunate. Ever since the Occupy movement so pithily pointed out the distance between the top earners and the rest, the inequalities of American life have been apparent to anyone with a flicker of sentience.

But the concept of class returns after a long period of retreat and transformation. For decades, class-based forms of critique were replaced by forms whose sources were not entirely or even primarily economic. For a time, the importance of social class as fundamental to explaining power imbalances—something taken for granted for generations—faded into the background.

The reasons why this happened are still obscure enough to be worth rehearsing. By the mid-1970s, in the wealthy Western countries, labor organizing had been successful enough to guarantee “middle-class” incomes to an enormous group of workers. Even unorganized workers reaped benefits. At the same time, the proportion of white-collar workers—professionals, clerks in offices, academics—came to exceed that of blue-collar workers. No matter how low their income, they tended to identify as middle class, and why not? Their work was clean, done amid bright lighting and powerful air-conditioning, and though they might be bossed around, they could at least dream of becoming the bosses themselves. Blue-collar workers, meanwhile, often earned more than their white-collar peers, and so potentially belonged to the middle, too.